my @a = ([  1,  8],
         [  9, 11],
         [ 20,  2],
         [ 22,  9],
         [ 31,  7],
         [ 38,  8],
         [ 46,  8],
         [ 54,  8],
         [ 62, 30],
         [ 92, 12],
         [104, 30]);
[download]

Or if your array is large, and you want to save memory:

my @b = (
    [1,  9, 20, 22, 31, 38, 46, 54, 62, 92, 104],
    [8, 11,  2,  8,  7,  8,  8,  8, 30, 12,  30]
);
[download]

But if you look carefully, the "keys" aren't necessary at all - if all you do is process the data in order, the keys can be calculated from the values, and all you need to keep is:

my @c = (8, 11,  2,  8,  7,  8,  8,  8, 30, 12,  30);
[download]

Abigail